Nimzo-Indian Defense: Hübner Variation, Rubinstein Variation, Main Line

A solid and flexible chess opening for Black, focusing on controlling the center and creating imbalances in pawn structure.

The opening is a popular choice among players who prefer a solid and flexible defense as Black. It is characterized by Black's early fianchetto of the dark-squared bishop, which exerts pressure on White's central pawn chain. The opening is named after two famous grandmasters, Hübner and Rubinstein, who contributed significantly to its development.

In this variation, White aims to maintain a strong pawn center while Black seeks to undermine it by exchanging pawns and creating imbalances in the pawn structure. Black's early development of the knight and bishop allows for quick castling and a safe king position. White's pawn on e3 supports the central pawn chain, while the knight on e2 is well-placed to support the advance of the f-pawn, potentially leading to a kingside attack.

The main line of this opening sees White playing a3, forcing Black to make a decision with the dark-squared bishop. Black can either capture on c3, doubling White's pawns and creating long-term weaknesses, or retreat the bishop to maintain the pin on the knight.

In the middlegame, both sides have chances for active play, with White typically aiming for a central pawn break or kingside attack, while Black looks to exploit weaknesses in White's pawn structure and create counterplay on the queenside.

Overall, the opening offers a rich and complex middlegame with plenty of strategic and tactical opportunities for both sides.